Two-thirds of L.A. Unified's fleet lacks the safety devices, officials say. Since July 2005, school buses built to carry more than 16 passengers are required to have three-point seat belts.

The school bus in which 21 people were injured when it flipped on its side after being broadsided by a speeding BMW in Boyle Heights is among hundreds of buses transporting students in the Los Angeles Unified School District that are not equipped with seat belts.

The school bus is a reflection of the district's aging fleet, in which two-thirds of the buses still lack restraints, according to district figures.

Since July 2005, school buses built to carry more than 16 passengers have been required to have three-point seat belts — the standard harness-style restraints common in cars. But the bus involved in Monday's crash was built just months before that law took effect in California, and is not required to have seat belts.

The district's aging inventory is in line with bus fleets throughout the state. According to a 2005 study by the advocacy group School Transportation Coalition — the most recent examination of buses in the state — the average age of school buses in the state is nearly 17 years.

The fleets of buses in California used to haul students to school, off-campus events and sporting competitions, often traveling by freeway, are "probably one of the oldest in the nation," said Stephen Rhoads, a legislative advocate for the coalition. He said the vast majority were built before the 2005 legislation.

L.A. Unified is purchasing 260 new buses that meet the 2005 seat belt requirement, said Robert Alaniz, a district spokesman. As the new buses roll in, the older models will be retired, he said.

The afternoon collision occurred when the teenage driver of the BMW ran a red light at First and Soto streets, struck and killed a pedestrian and plowed into the bus, authorities said. The bus was upended and skidded into a plaza outside a Metro station, tossing many of the 46 student-passengers from their seats.

The bus is one of many operated by First Student, one of several private companies contracted by the district. About a third of the buses carrying L.A. Unified students are operated by private firms.

The lack of severe injuries in a violent accident like Monday's collision, however, attests to the general safety of school buses, said Enrique Boull't, the district's director of transportation.

"It's because students were in a school bus that they had relatively minor injuries," Boull't said. "The driver did a remarkable job protecting the students."

The California Highway Patrol is investigating whether the 17-year-old driver of the BMW and his two passengers, 17 and 14, were under the influence when the car roared into the intersection. The driver, who was arrested along with one of the passengers as they ran from the scene, is expected to face felony hit-and-run charges and potentially a manslaughter charge, investigators said.

One of the teenagers was identified as a student at Roosevelt High School, the campus where the buses was headed. Authorities have not identified the youths because of their ages. All are being held at Los Angeles County Juvenile Hall.

Eduardo Gayton, a 70-year-old grandfather of three, was in the crosswalk when he was hit by the speeding car, investigators said. He was pronounced dead at the scene.

Gayton, who lived nearby, was in the area shopping and, according to his family, didn't like to drive, preferring to walk or take public transportation.

"It is really terrible. He didn't have a chance," said Margarita Gaytan, his ex-wife, who was speaking outside her former husband's home. "The car was coming so fast."

Some of the students were shaken and bloodied as they crawled from the wreckage of the bus. One student, 16-year-old Susana Romero, said she blacked out after being hurled from her seat to the other side of the bus.

"It made us fly," she said.

Several parents who rushed to the scene of the collision wondered why there were no restraints in the bus. "In our cars we have to have them, why not in our buses?" asked Hugo Landa, the stepfather of one of the passengers. "They're students!"

On Tuesday, students and teachers at Roosevelt High were shaken, yet thankful that no students were seriously injured. The students who were riding the bus are among the several hundred who take classes at East Los Angeles Skills Center, because of overcrowding.

"They are like family," Principal Sofia Freire said. "There are only 300 kids, so they all know each other. They were talking about the classmates they noticed that weren't there."

Freire said she was at the hospital Monday night with the students and their families. On Tuesday morning, she visited many of the students again — this time by riding with them on the school bus.